1. Field of the Invention
The present invention relates to a lubricant supplying device, an image forming apparatus, and a process cartridge.
2. Description of the Related Art
In image forming apparatuses such as printers, facsimiles, and copying machines, the image forming apparatuses have been known that include lubricant supplying devices supplying lubricant to surfaces of image carriers for protection or reducing friction of photosensitive elements and intermediate transfer belts serving as image carriers (e.g., Japanese Patent Application Laid-open No. 2007-293240).
FIGS. 28A and 28B are schematic structural views of a lubricant supplying device described in Japanese Patent Application Laid-open No. 2007-293240. FIG. 28A illustrates a state at the beginning of use. FIG. 28B illustrates a state at which solid lubricant 162 is exhausted. FIGS. 28A and 28B illustrate a structure on one end side in a longitudinal direction of the solid lubricant 162. The other end side also has the same structure. As illustrated in FIG. 28A, the lubricant supplying device described in Japanese Patent Application Laid-open No. 2007-293240 includes a supplying member 161 that abuts the solid lubricant 162 having a bar shape, scrapes the solid lubricant 162 by making a sliding contact with and rubbing the solid lubricant 162, and supplies the powdered lubricant after the scraping to an image carrier. In addition, the lubricant supplying device includes a lubricant holding member 164 holding the side, which is opposite the side at which the solid lubricant 162 abuts the supplying member 161, of the solid lubricant 162. The lubricant holding member 164 is housed in a case 165 of the lubricant supplying device such that the lubricant holding member 164 can move in an approaching-and-distancing direction of the solid lubricant 162 relative to the supplying member 161. Furthermore, in a space on the side, which is opposite the side at which the lubricant holding member 164 holds the solid lubricant 162, of the lubricant holding member 164 in the case 165, a pushing mechanism 163 is provided that pushes the side, which is opposite the side at which the lubricant holding member 164 holds the solid lubricant 162, of the lubricant holding member 164 toward the supplying member 161.
The pushing mechanism 163 has a pair of swing members 163A, one end side of each of which is provided on the lubricant holding member 164 in a swingable manner, disposed symmetrically about the center in the longitudinal direction of the solid lubricant 162 (the swing member 163A on the other end side in the longitudinal direction of the lubricant holding member 164 is not illustrated). Respective both ends of a spring 163C serving as a biasing unit are attached to the swing members 163A. Each swing member 163A receives from the spring 163C a biasing force acting toward the center in the longitudinal direction of the lubricant holding member 164 as illustrated with arrow D in FIG. 28A. The biasing force urges the other end side (hereinafter referred to as a swing end) of each swing member 163A to leave from the lubricant holding member 164 as illustrated in FIG. 28A, resulting in the swing end abutting a surface 165A facing the lubricant holding member 164 of the case 165. The lubricant holding member 164 abuts the supplying member 161 with a certain abutting force by being pushed toward the supplying member 161 by a reaction force of a pushing force of the swing members 163A (force acting downward in FIG. 28A) applied to the surface 165A of the case 165.
With the rotation of the supplying member 161, the supplying member 161 makes a sliding contact and rubs the solid lubricant 162, which abuts the supplying member 161. Lubricant scraped from the solid lubricant 162 by the sliding contact and rubbing and stuck to the supplying member 161 is applied to a surface of the image carrier. As the solid lubricant 162 is gradually scraped by the sliding contact and rubbing of the supplying member 161, the swing members 163A swing, resulting in the lubricant holding member 164 moving toward the supplying member 161 as illustrated in FIG. 28B. The solid lubricant 162 continues to abut the supplying member 161 from the beginning to an end stage of use, thereby enabling the supplying member 161 to scrape the solid lubricant 162 well.
When image forming operation is performed without supply of lubricant, an image carrier is damaged by being worn because there is no protective effect of the lubricant. Thus, it is necessary to detect that an amount of remaining lubricant is small (detect a near-end) and replace the lubricant with new lubricant. The inventors of the present invention prototyped a lubricant supplying device as illustrated in FIG. 29 (hereinafter referred to as the prototype).
As illustrated in FIG. 29, in the prototype, a first electrode member 171 serving as a first detection member is provided at a position in a sliding area S, on which the swing member 163A slides, of the surface 165A facing the lubricant holding member 164 of the case 165. The swing member 163A abuts the position when the remaining amount of the solid lubricant 162 is small. A second electrode member 172 serving as a second detection member is provided at a position in an abutting area 163A of the swing member 163A abutting the sliding area S of the case 165. The swing member 163A abuts the position when the remaining amount of the solid lubricant 162 is small (near-end).
In the prototype, when the remaining amount of the solid lubricant 162 is small (near-end), the second electrode member 172 provided in an abutting area 163B of the swing member 163A abuts the first electrode member 171 provided in the sliding area S of the case 165. As a result, conduction is established between the first electrode member 171 and the second electrode member 172 and a current flows between the electrode members 171 and 172. This current enables a detection unit 173 to detect the near-end of the solid lubricant 162.
In the prototyped lubricant supplying device, however, a new problem arose in that the lubricant was not applied uniformly on the surface of the image carrier in some cases. Specifically, the lubricant holding member 164 is housed in the case 165 with a certain amount of backlash therebetween because the lubricant holding member 164 needs to be allowed to move inside the case 165. As a result, the position of the lubricant holding member 164 shifts in the longitudinal direction of the solid lubricant 162 during use in some cases. The shift in the position of the lubricant holding member 164 in the longitudinal direction causes the swing member 163A attached swingably to the lubricant holding member 164 to shift in the longitudinal direction. As a result, the swing member 163A abuts the first electrode member 171 of the case 165 at a different position in the abutting area 163B from the position at which the second electrode member 172 is provided. Sliding resistance differs when the swing member 163A slides on the internal surface of the case 165 and when the swing member 163A slides on the surface of the first electrode member 171 of the case 165 because a friction coefficient differs between the first electrode member 171 provided on the case 165 and to the case 165. As a result, the sliding resistance differs between the swing member 163A on one side, which slides on the first electrode member 171, and the swing member 163A on the other side, which slides on the case 165, resulting in a swing amount of the swing member 163A differing between one side and the other side. This difference disables the solid lubricant 162 to abut the supplying member 161 with uniform abutting pressure in the longitudinal direction, thereby causing an amount of the lubricant scraped by the supplying member 161 to differ in the longitudinal direction. As a result, the lubricant cannot be applied uniformly on the surface of the image carrier.
In view of the above, there is a need to provide a lubricant supplying device that can detect that a remaining amount of lubricant is small and can prevent non-uniformity of an amount of the lubricant supplied to a supply target caused by the swing member sliding on the first detection member, an image forming apparatus using the lubricant supplying device, and a process cartridge using the lubricant supplying device.